As gambling is legalized throughout the United States, the number of publicly funded treatment programs for compulsive gamblers has increased. Treatment programs have been established in several states in spite of the lack of data on the nature and extent of compulsive gambling. Data from a pilot study in New York State indicate that compulsive gambling treatment programs are not serving the entire range of problem gamblers in the state. Since several states have based their programs on the New York model, the possibility that the entire range of compulsive gamblers is not being reached in other states is high. Discrepancies between prevalence and program data suggest that professional staff screen clients for characteristics which do not reflect the full range of variation among compulsive gamblers in the general population. Using a sample of five states which have established or mandated the establishment of publicly funded treatment programs, the research proposed here will collect data on prevalence as well as on program staff and clients in order to assess the sources of variation between compulsive gambling in the general population and compulsive gamblers in treatment. The proposed project can be expected to contribute to knowledge and practice in several areas, including: (a) the targeting of efforts by administrative and clinical staff serving compulsive gamblers in establishing appropriate screening procedures and treatment interventions for compulsive gamblers, (b) the allocation of appropriate services by mental health professionals, and (c) social science knowledge about the relationship between theory and methods.